Retinoids regulate expression of the retinol-binding protein gene in hepatoma cells in culture

The expression of the gene coding for retinol-binding protein has been studied in a system of cultured human hepatoma cells exposed to retinoids. We report that the gene is positively modulated by retinol and retinoic acid in a time- and dose-dependent fashion. The stimulation at the mRNA level is paralleled by an increase of the corresponding protein that is secreted in the presence of the physiological ligand. An RBP-CAT chimeric gene, introduced by transfection, is also responsive to the treatment, showing the gene dose-dependency as the endogenous gene. These results demonstrate that retinoids up-regulate the RBP gene and that the control takes place at transcriptional level.